In the manufacture of furniture, cabinets, counters, and the like it is standard to adhere a decorative cover tape to the edge of a board. Frequently chipboard or the like is laminated on one of its broad faces with a decorative and/or protective covering or veneer and a tape of a similar such covering is then applied to the board edges to impart the same appearance or properties to them also. As a rule contact or thermally activatable adhesives are used to hold the tape on.
When the workpiece is a board with straight edges, this application of the tape to its edge is easily completed as the workpiece moves along an assembly line in a direction parallel to the edge being taped. The workpiece can be turned to similarly tape its remaining edges. When, however, the workpiece does not have straight edges the task is substantially more difficult.
A standard machine for dealing with such nonstraight edges has a small table to which the workpiece is clamped, normally with the main plane of the workpiece horizontal and the workpiece edges overhanging the table. This table can be rotated about a vertical axis passing through the workpiece. Adjacent the table is an arm having an outer end pivoted about another vertical axis and an inner end carrying a roller with the arm extending generally tangentially of the workpiece. The arm is spring-loaded to press this roller radially inward of the table axis against the workpiece to press an adhesived tape against the workpiece edge while the workpicce rotates. Another such arm upstream in the workpiece rotation direction can carry a tool that mills, grinds, or otherwise machines the workpiece edge, typically to cut back the surface laminate level with the edge.
Such a machine cannot be operated readily by an numerical-type controller because relative to the workpiece that is fixed to the work station, a working plane must be set in which every point must be accessible in two directions. Since the starting position of the workpiece is not determinable and also because the roller arm oscillates, that is moves the roller through an arc intersecting the workpiece edge as the roller follows the workpiece edge, such a controller cannot be used due to the complexity of calculating location based on a nonstraight roller path intersecting an edge of an irregular figure rotating about an indeterminate center.
On the other hand a trimming machine is known which can round edges or cut off projecting laminate by means of a tool that travels around the edge of a stationary workpiece. This machine has a support carrying the tool, typically a roller-type router bit, and movable horizontally in two perpendicular directions to guide this bit around the workpiece. Such a machine typically precedes and is wholly separate from the above-described rotary-table machine for taping the edges of the workpiece after it is trimmed.